Electrical outlets distribute power via a three socket connector having contacts connected to a line conductor, a neutral conductor and ground. Traditional circuit breakers protect against current surges or short circuits by detecting an overcurrent from downstream electrical outlets connected to branch wiring. The circuit breaker interrupts power via a trip mechanism when a current surge or short circuits are detected. Traditional circuit breakers cannot detect other faults such as arc faults which may occur in the outlet or wiring to the outlets, posing safety hazards. Thus, various other fault detection and protection devices are required for safety reasons in relation to electrical power distribution. For example, ground fault circuit interrupter (GFCI) outlets have been standard required equipment for a number of years. Such devices protect against faults occurring on the ground line. Additional protection is desired for other types of faults such as arc faults which occur on the line and neutral conductors. For example, arc fault detection is required in the form of an arc fault circuit interrupter (AFCI) device in outlets for safety reasons. Such devices detect current arc faults on the line and neutral conductors and cut off power before such arcs can cause an electrical fire. Such AFCI protected outlets provide protection against arcing thus decreasing the risk of electrical fires. AFCI devices must analyze arcs to determine whether the arc is a result of conventional use of an electrical outlet such as turning on a load device or whether the arc is a fault which could threaten to cause a fire.
Present AFCI devices perform arc fault detection by running a complicated probability based algorithm to detect whether a detected arc event constitutes a series or parallel arc fault in branch wiring downstream from the AFCI device. Some non-probability (impedance) based arc fault detection algorithms methods exist that require complete calibration to the circuit and load in a non-fault condition in memory for comparison with sensed values during the AFCI device operation. Algorithms detect any deviation from the calibrated values to determine whether an arc fault exists. With a probability based algorithm unwanted tripping caused by load incompatibility is an issue since such a load may fall outside of the calibrated values but may not be an arc fault. Intense troubleshooting is then required to determine if the trip was due to an actual arc fault or load incompatibility.
There is therefore a need for an AFCI device that detects arcing conditions with impedance measurement thus eliminating the need for a probability based algorithm and the associated troubleshooting between actual faults in branch wiring and potential load incompatibility. There is a further need for a system for arc detection using impedance measurement without the need for complete circuit calibration. There is also a need for an AFCI system that allows a user to detect the particular location of a series fault. There is also a need for an AFCI system that allows a user to detect parallel arc faults.